MathDiscussion forum for anything math related.Mon, 19 Mar 2018 14:33:42 +0000Mon, 19 Mar 2018 14:33:42 +0000All About Circuitshttps://forum.allaboutcircuits.com/forums/math.8/
Finding linear regression equation with unequal sample sizesThu, 15 Mar 2018 01:49:04 +0000https://forum.allaboutcircuits.com/threads/finding-linear-regression-equation-with-unequal-sample-sizes.146680/
https://forum.allaboutcircuits.com/threads/finding-linear-regression-equation-with-unequal-sample-sizes.146680/invalid@example.com (asilvester635)asilvester635
I just need help with the calculations. Once I know how to do the calculations I can just translate that into java code.

View attachment 148331]]>3How did the highlighted part become zero ?Wed, 14 Mar 2018 02:43:20 +0000https://forum.allaboutcircuits.com/threads/how-did-the-highlighted-part-become-zero.146616/
https://forum.allaboutcircuits.com/threads/how-did-the-highlighted-part-become-zero.146616/invalid@example.com (Damien De Silva)Damien De SilvaView attachment 148213]]>6Another math problem (fun)Fri, 02 Mar 2018 03:41:12 +0000https://forum.allaboutcircuits.com/threads/another-math-problem-fun.141975/
https://forum.allaboutcircuits.com/threads/another-math-problem-fun.141975/invalid@example.com (MrChips)MrChips
They each give $10 to the waiter. The waiter goes to the cashier who notices that the waiter had made a mistake in tallying the tab. The correct total is $25. The cashier gives the waiter five $1 coins in change (they don't print $1 bills anymore).

On the way back to the table, the waiter ponders on how he is going to split $5 three ways.
No problem, he thinks. "They think the total...

The fact that newborn chicks, fish and human neonates can make numerical discriminations suggests that this capacity does not arise as a result of interaction with the environment, but is inherited though subsequent interaction with environment doubtless modifies and refines the operation of this mechanism. It is also the case, as Butterworth...

Click to expand...

The origins of numerical abilities]]>Demodulating a filtered signalSun, 04 Feb 2018 19:26:25 +0000https://forum.allaboutcircuits.com/threads/demodulating-a-filtered-signal.143730/
https://forum.allaboutcircuits.com/threads/demodulating-a-filtered-signal.143730/invalid@example.com (Pedro Malabarte)Pedro Malabarte
Since at any given point in time the filtered signal is the weighed average of many previous points, whatever change the amplitude of a constant frequency signal is irrevocably lost.

For instance, if I filter a simple sine wive that is within my passbound limits, I still get the same wave as a result. Okay. But if the signal is, say, one period...

Demodulating a filtered signal]]>21Multiply input directly to the tranfer function/frequency responseSun, 04 Feb 2018 18:52:39 +0000https://forum.allaboutcircuits.com/threads/multiply-input-directly-to-the-tranfer-function-frequency-response.143963/
https://forum.allaboutcircuits.com/threads/multiply-input-directly-to-the-tranfer-function-frequency-response.143963/invalid@example.com (jag1972)jag1972
Wanted to ask you for some advice as I am a little stuck on a 1st order FIR low pass filter question

If the following input signal (which is made up of 2 components) is applied to the low pass filter:

Using superposition the out signal can be determined. If we assume that ,

Rules:
Don't post the answer if you already know it. The challenge is to figure it out from scratch. Who will be first ?

It will be interesting to see how different people approach the problem.

WARNING
Those of faint heart best not indulge.

This puzzle is way harder than it looks.
It was first solved in the 1600's and considered one of the greatest achievements.
I started looking at it 5 years ago, with a few clues, and only worked it...

Cubic Solution Puzzle]]>11How many games should be in the match [rec puzzle]Sun, 28 Jan 2018 15:52:42 +0000https://forum.allaboutcircuits.com/threads/how-many-games-should-be-in-the-match-rec-puzzle.144200/
https://forum.allaboutcircuits.com/threads/how-many-games-should-be-in-the-match-rec-puzzle.144200/invalid@example.com (WBahn)WBahn
Not surprisingly, the more games that constitute a match the greater the likelihood that the better team will win the match. But if the teams are almost evenly matched, it can take a large number of games before the likelihood that the better team will win the match becomes...

How many games should be in the match [rec puzzle]]]>12Describing a sinusoidal signal mathematically and it's uses.Mon, 22 Jan 2018 16:54:10 +0000https://forum.allaboutcircuits.com/threads/describing-a-sinusoidal-signal-mathematically-and-its-uses.144454/
https://forum.allaboutcircuits.com/threads/describing-a-sinusoidal-signal-mathematically-and-its-uses.144454/invalid@example.com (richard3194)richard3194
Let's begin with this simple equation: ν = A sin θ. I'm not sure you could say it describes the signal. What I am sure about is that if someone sets a question and asks me to calculate ν, as long as I'm told the angle (theta) I can do it. If , in a question, A is 200V (Voltage at peak:...

Describing a sinusoidal signal mathematically and it's uses.]]>38R L C circuitSat, 20 Jan 2018 01:51:52 +0000https://forum.allaboutcircuits.com/threads/r-l-c-circuit.30107/
https://forum.allaboutcircuits.com/threads/r-l-c-circuit.30107/invalid@example.com (lil coob)lil coob
i am stuck on how to find the resistor and coil values on this circuit.
i have been given the following:

any help would be much appreciated
many thanks]]>14Ternary Notation: Revisiting 12 coins [Mathematical Recreation]Sat, 13 Jan 2018 14:47:12 +0000https://forum.allaboutcircuits.com/threads/ternary-notation-revisiting-12-coins-mathematical-recreation.144317/
https://forum.allaboutcircuits.com/threads/ternary-notation-revisiting-12-coins-mathematical-recreation.144317/invalid@example.com (Raymond Genovese)Raymond Genovese
You have 12 coins and a balance scale. One of the coins is counterfeit. You can use the balance scale exactly three times, placing however many coins you want in the pans. After those three weighing, you have to determine which coin is counterfeit and whether it is heavy or light.

There are no tricks. Eleven coins weigh the same and one coin is different,...

Ternary Notation: Revisiting 12 coins [Mathematical Recreation]]]>8Shortest strings having divisibility properties in both directions.Sat, 13 Jan 2018 05:07:02 +0000https://forum.allaboutcircuits.com/threads/shortest-strings-having-divisibility-properties-in-both-directions.144111/
https://forum.allaboutcircuits.com/threads/shortest-strings-having-divisibility-properties-in-both-directions.144111/invalid@example.com (WBahn)WBahn
Imagine a string of 0's and 1's (call it 's') and the reverse of the string (call it 'r'). For instance

s = 1100
r = 0011

Now, interpret 's' as a base-2 value and interpret 'r' as a base-3 value.

s = 1100 (base-2 = 12)
r = 0011 (base-3 = 4)

If 's' is a string such that 's' is divisibly by 3 but 'r' is NOT divisible by 2, then we put 's' into a collection of strings and call that collection the language L....

Shortest strings having divisibility properties in both directions.]]>19Two-out-of-three probability [recreational puzzle]Tue, 09 Jan 2018 17:25:03 +0000https://forum.allaboutcircuits.com/threads/two-out-of-three-probability-recreational-puzzle.144194/
https://forum.allaboutcircuits.com/threads/two-out-of-three-probability-recreational-puzzle.144194/invalid@example.com (Raymond Genovese)Raymond Genovese
If they play a “best of 3” match, how often can we expect player X to win?

How about if X’s odds of winning a game are .70 or .80 or .90?]]>2Potentially fun math problemSun, 07 Jan 2018 04:56:49 +0000https://forum.allaboutcircuits.com/threads/potentially-fun-math-problem.144109/
https://forum.allaboutcircuits.com/threads/potentially-fun-math-problem.144109/invalid@example.com (Raymond Genovese)Raymond Genovese

The length of bolts made in factory Z is normally distributed, with a mean length of 0.1630 meters and a standard deviation of 0.0084 meters. The probability that a randomly selected bolt is between...

In the lower plot there are many WINDOW SAMPLES (separated by vertical lines); thus for every sample in window width, we compute SIGNAL SAMPLES .* WINDOW SAMPLES.

Then we JOIN all previous products and get the FULL WINDOWED SIGNAL; on this finally signal we calculate Y = fft(FULL WINDOWED SIGNAL, N fft points)

Is the...

Windowed fft: how windowing is practically applied at overall data?]]>2Resistor Cube PropertiesThu, 14 Dec 2017 19:30:01 +0000https://forum.allaboutcircuits.com/threads/resistor-cube-properties.135837/
https://forum.allaboutcircuits.com/threads/resistor-cube-properties.135837/invalid@example.com (MrAl)MrAl
I started working on the resistor cube problem that we started thinking about in the resistor grid thread. Here are some results:

View attachment 140628View attachment 140629]]>3How do I find the output voltage of my simple Royer oscillator?Thu, 30 Nov 2017 10:33:06 +0000https://forum.allaboutcircuits.com/threads/how-do-i-find-the-output-voltage-of-my-simple-royer-oscillator.142768/
https://forum.allaboutcircuits.com/threads/how-do-i-find-the-output-voltage-of-my-simple-royer-oscillator.142768/invalid@example.com (kasperzacho)kasperzacho
I am trying to find an expression for the output voltage of my Royer oscillator. I have attached the oscillator as a file to this post.
I understand how the system works in practice and theory. However I need some help finding an expression for the voltage across L4.